US Physics Chapter 18 Hemodynamics
Terms
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- study of blood flow
- hemodynamics
- volume moving at a particular time
- flow
- speed of a fluid moving from one location to another
- velocity
- units for velocity
- distance/time
- 3 forms of flow
-
pulsatile
phasic - 3 forms of flow:
-
pulsatile
phasic -
constant speed
venous(holding breath) - steady flow
-
variable velocitie
heart causes it - pulsatile
-
variable velocities
respirations change it
- phasic
- normal phasic respiration
- 5 breaths/minute
-
layers of bld. flow parallel to each other but at individual speeds
found in normal states - laminar flow
- 2 forms of laminar flow
-
plug
parabolic - all travel at the same speed (found at entrance to vessel) *type of laminar flow*
- plug
- bullet profile, fastest in center, slowest at vessel wall(normal vessel)
- parabolic
- chaotic flow pattern, many speeds and directions
- turbulent flow
- cardiovascular path causes ___flow
- turbulent flow
- turbulent flow is seen ____to stenosis
- distal
- ____are like a hurricane pattern
- eddy currents
- heard with a stethoscope
- murmur or bruit
- felt with fingertips, palp murmur
- thrill
- causes blood to flow
- energy gradient
- the difference in fluid energy from one end to another
- energy gradient
- Total energy= _____
- kinetic pressure gravitational
- energy in motion
- kinetic
- 2 determining factors of kinetic energy
-
speed it moves
objects mass - form of stored or potential energy; has ability to perform work; used to overcome resistance in circulation
- pressure energy
- form of stored or potential energy; deals with elevated objects;
- gravitational energy
- types of energy losses
- viscous, frictional, inertial
- thickness of fluid
- viscosity
- measured in poise
- viscous loss
- % of rbcs in blood
- hematocrit
- flow energy is converted to heat
- frictional energy loss
- tendency of a fluid to resist changes iin its velocity (how fast)
- inertial energy loss
- lose energy if speeding up or slowing down
- inertial energy loss
- 3 events that cause inertial energy loss
-
pulsatile flow
phasic flow - 3 events that cause inertial energy loss:
-
pulsatile
phasic
stenosis -
-where vessel narrows
-changes flow in and ot of narrowing
-highest velocity found at tightest narrowing - stenosis
- turbulent flow
- post stenosis
- pressure downstream is ____than upstream
- lower
- pulsatile flow turns to ___ in stenosis
- steady flow
- In stenosis, pressure downstream is ____than upstream
- lower
- pressure gradient =
- flow x resistance
- flow increases if pressure gradient ___ or resistance ____
- increases; decreases
- flow =
- pressure grad/ resistance
- ohms law=
- voltage= current x resistance
-
venous hemodynamics
normal shape of vein is ___ - flattened or hourglass
- veins are ____, have ____walls, and have ____resistance
- collapsible, thin, low
- veins do what when excersising?
- dilate to rounded shape
- pressure that expands veins
- transmural pressure
- pressure in relation to heart, whether above or below, of blood pressing on vessel at that location
- hydrostatic pressure
- unit for hydrostatic pressure
- mmHg
- hydrostatic pressure when supine:
- 0
- above heart at head when standing:
- -30
- mid chest standing
- 0
- total measured pressure=
- circulatory pressure +hydrostatic pressure
- during inspirtation, diaphragm moves downward. ___thoracic pressure. ___flow in legs. ___abdomen pressure. _____in flow in arms and IVC
- low, low, increase, increase
- In expiration, diaphragm moves up. ___flow in legs. ___pressure in thorax. ___abd pressure. ___in flow in arms/IVC
- increase, increase, decrease, decrease